High-throughput screening of 11beta-hydroxysteroid dehydrogenase type 1 in scintillation proximity assay format

11beta-Hydroxysteroid dehydrogenase type-1 (11beta-HSD1) is a potential target for the treatment of diabetes, obesity, and hyperlipidemia. This enzyme is mainly responsible for reactivating glucocorticoid hormone inside cells such as adipose cells and liver cells by converting the inactive cortisone to active cortisol. Enzyme assays for 11beta-HSD1 involve either a thin-layer chromatography or high-performance liquid chromatography step to separate cortisol from the substrate cortisone. This additional step is labor intensive and increases the assay time, which limits assay throughput. A homogenous scintillation proximity assay-based method has been recently developed that enables high-throughput screening of 11beta-HSD1 inhibitors. We have applied this novel 11beta-HSD1 assay to screening a large-size compound collection and identified several structural classes of lead compounds that selectively inhibit the activity of 11beta-HSD1.     

The discovery of new 11beta-hydroxysteroid dehydrogenase type 1 inhibitors by common feature pharmacophore modeling and virtual screening

11beta-Hydroxysteroid dehydrogenase (11beta-HSD) enzymes catalyze the conversion of biologically inactive 11-ketosteroids into their active 11beta-hydroxy derivatives and vice versa. Inhibition of 11beta-HSD1 has considerable therapeutic potential for glucocorticoid-associated diseases including obesity, diabetes, wound healing, and muscle atrophy. Because inhibition of related enzymes such as 11beta-HSD2 and 17beta-HSDs causes sodium retention and hypertension or interferes with sex steroid hormone metabolism, respectively, highly selective 11beta-HSD1 inhibitors are required for successful therapy. Here, we employed the software package Catalyst to develop ligand-based multifeature pharmacophore models for 11beta-HSD1 inhibitors. Virtual screening experiments and subsequent in vitro evaluation of promising hits revealed several selective inhibitors. Efficient inhibition of recombinant human 11beta-HSD1 in intact transfected cells as well as endogenous enzyme in mouse 3T3-L1 adipocytes and C2C12 myotubes was demonstrated for compound 27, which was able to block subsequent cortisol-dependent activation of glucocorticoid receptors with only minor direct effects on the receptor itself. Our results suggest that inhibitor-based pharmacophore models for 11beta-HSD1 in combination with suitable cell-based activity assays, including such for related enzymes, can be used for the identification of selective and potent inhibitors.     

The role of 11beta-hydroxysteroid dehydrogenase in metabolic disease and therapeutic potential of 11beta-hsd1 inhibitors

Glucocorticoids play an essential role in the regulation of multiple physiological processes, including energy metabolism, maintenance of blood pressure and stress responses, as well as cognitive functions. On a tissue-specific level, glucocorticoid action is controlled by 11beta-hydroxysteroid dehydrogenase enzymes. The type 1 enzyme (11beta-HSD1) is a NADP(H)-dependent bidirectional enzyme in vitro and reduces cortisone to active cortisol in vivo. 11beta-HSD1 is expressed in many tissues including the liver, adipose and skeletal muscles. Chronically elevated local glucocorticoid action as a result of increased 11beta-HSD1 activity has been associated with the metabolic syndrome, which is characterized by obesity, insulin resistance, type 2 diabetes and cardiovascular complications. Recent studies indicate that the inhibition of 11beta-HSD1 mitigates the adverse effects of excessive glucocorticoid levels on metabolic parameters and provides promising opportunities for the development of therapeutic interventions. This review discusses recently disclosed 11beta-HSD1 inhibitors and their potential for the treatment of metabolic disorders.     

Dehydroepiandrosterone metabolites and their interactions in humans

Dehydroepiandrosterone (DHEA) is 7alpha-hydroxylated by the cytochrome P4507B1 in the liver, skin and brain, which are targets for glucocorticoids. 7alpha-Hydroxy-DHEA produced anti-glucocorticoid effects in vivo but the interference between the glucocorticoid hormone binding with its receptor could not be determined. In the organs mentioned above, circulating inactive cortisone is reduced to active cortisol by 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1). 7alpha-Hydroxy-DHEA is also a substrate for this enzyme. Studies of 11beta-HSD1 action on 7alpha-hydroxy-DHEA show the reversible production of 7beta-hydroxy-DHEA through an intermediary 7-oxo-DHEA. Both the production of 7alpha-hydroxysteroids and their interference with the activation of cortisone into cortisol are basic to the concept of native anti-glucocorticoids. The cytochrome P4507B1 responsible for 7alpha-hydroxy-DHEA production and 11beta-HSD1 are key enzymes for the modulation of glucocorticoid action in humans. This is a promising new area for research.     

Readjusting the glucocorticoid balance: an opportunity for modulators of 11beta-hydroxysteroid dehydrogenase type 1 activity?

Glucocorticoids play a pivotal role in the regulation of most essential physiological processes, including energy metabolism, maintenance of electrolyte balance and blood pressure, immune-modulation and stress responses, cell proliferation and differentiation, as well as regulation of memory and cognitive functions. There are several levels at which glucocorticoid action can be modulated. On a tissue-specific level, glucocorticoid action is tightly controlled by 11beta-hydroxysteroid dehydrogenase (11beta-HSD) enzymes. The conversion of inactive 11-ketoglucocorticoids (cortisone and 11-dehydrocorticosterone) into active 11beta-hydroxyglucocorticoids (cortisol and corticosterone) is catalyzed by 11beta-HSD1, which is expressed in many tissues and plays an important role in metabolically relevant tissues such as the liver, adipose tissue and skeletal muscles. Chronically elevated local glucocorticoid action as a result of increased 11beta-HSD1 activity rather than elevated systemic glucocorticoid levels has been associated with metabolic syndrome, which is characterized by obesity, insulin resistance, type 2 diabetes and cardiovascular complications. Recent studies indicate that compounds inhibiting 11beta-HSD1 activity ameliorate the adverse effects of excessive glucocorticoid concentrations on metabolic processes, providing promising opportunities for the development of therapeutic interventions. This review addresses recent findings relevant for the development and application of therapeutically useful compounds that modulate 11beta-HSD1 function.     

Glucocorticoids and vascular reactivity

Corticosteroid hormones play an important role in the control of vascular smooth muscle tone by their permissive effects in potentiating vasoactive responses to catecholamines through glucocorticoid receptors. Increased cortisol response has been associated with an increase in arterial contractile sensitivity to norepinephrine and vascular resistance. Glucocorticoids regulate vascular reactivity by acting on both endothelial and vascular smooth muscle cells. Both glucocorticoid receptor protein and mRNA have been identified in endothelial and vascular smooth muscle cells. In endothelial cells. glucocorticoids suppress the production of vasodilators. such as prostacyclin and nitric oxide. In vascular smooth muscle cells. glucocorticoids enhance agonist-mediated pharmacomechanical coupling at multiple levels. The effect of glucocorticoids on vascular reactivity is regulated by 11 beta-hydroxysteroid dehydrogenase (11beta-SD). The presence of 11beta-HSD in many tissues suggests that it modulates the access of corticosteroids to their receptors at both renal and extra-renal sites. The two 11beta-HSD isozymes catalyze the interconversion of cortisol and cortisone. Type 11beta-HSD has bidirectional activity, while the type 2 mainly converts cortisol into cortisone, the biologically inactive form. Both type 1 and type 2 11beta-HSD have been found in vascular endothelial and smooth muscle cells, suggesting that abnormal 11B-HSD expression may play a pathogenic role in the common forms of hypertension. In this article, we review possible mechanisms involved in the glucocorticoid-mediated potentiation of vascular reactivity, its regulation by 11beta-HSD, and their physiological and pathophysiological significance.     

Inhibition of 11beta-hydroxysteroid dehydrogenase type 1 as a promising therapeutic target

Chronically elevated glucocorticoid levels cause obesity, diabetes, heart disease, mood disorders and memory impairments. 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1) catalyses intracellular regeneration of active glucocorticoids (cortisol, corticosterone) from inert 11-keto forms in liver, adipose and brain, amplifying local action. Obese humans and rodents show increased 11beta-HSD1 in adipose tissue. Transgenic mice overexpressing 11beta-HSD1 selectively in adipose tissue faithfully recapitulate metabolic syndrome. Conversely, 11beta-HSD1 knockout mice have a 'cardioprotective' phenotype, whose effects are also seen with 11beta-HSD1 inhibitors in rodents. However, any major metabolic effects of 11beta-HSD1 inhibition in humans are, as yet, unreported. 11beta-HSD1 null mice also resist cognitive decline with ageing, and this is seen in humans with a prototypic inhibitor. Thus 11beta-HSD1 inhibition is an emerging pleiotropic therapeutic target.     

Human 11beta-hydroxysteroid dehydrogenase 1/carbonyl reductase: recombinant expression in the yeast Pichia pastoris and Escherichia coli

Detoxification of aldehydes and ketones generally proceeds via reduction to their corresponding alcohols, which are then conjugated and eliminated. We focused our interest on 11beta-hydroxysteroid-dehydrogenase type 1 (11beta-HSD 1), a pluripotent enzyme which physiologically performs the interconversion of active and inactive glucocorticoid hormones, and which also participates in xenobiotic carbonyl compound detoxification. 11beta-HSD 1 belongs to the protein superfamily of the short-chain dehydrogenases/reductases (SDR), and has been structurally and functionally characterized. 11beta-HSD 1 is a glycosylated membrane protein which is very difficult to purify in an active state. In addition, expression levels in humans differ in a wide range. In order to facilitate biochemical and molecular studies on the significance of human 11beta-HSD 1 in detoxification processes, we have successfully performed the overexpression of recombinant human 11beta-HSD 1 in the yeast Pichia pastoris and in Escherichia coli. Recombinant 11beta-HSD 1 from E. coli was purified to homogeneity and used to generate a polyclonal antibody. The enzyme had no enzymatic activity, possibly due to the lack of glycosylation and/or incorrect folding in E. coli. In contrast, 11beta-HSD 1 overexpressed in P. pastoris was enzymatically active towards its physiological glucocorticoid substrates as well as towards xenobiotic carbonyl compounds. In western blot experiments the antibody crossreacted with both recombinant 11beta-HSD 1 forms and with the native enzyme from mouse and human liver. In conclusion, recombinant 11beta-HSD 1 from P. pastoris serves as a valuable tool for future studies on carbonyl compound detoxification.     

2-amino-1,3-thiazol-4(5H)-ones as potent and selective 11beta-hydroxysteroid dehydrogenase type 1 inhibitors: enzyme-ligand co-crystal structure and demonstration of pharmacodynamic effects in C57Bl/6 mice

11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1) has attracted considerable attention during the past few years as a potential target for the treatment of diseases associated with metabolic syndrome. In our ongoing work on 11beta-HSD1 inhibitors, a series of new 2-amino-1,3-thiazol-4(5 H)-ones were explored. By inserting various cycloalkylamines at the 2-position and alkyl groups or spirocycloalkyl groups at the 5-position of the thiazolone, several potent 11beta-HSD1 inhibitors were identified. An X-ray cocrystal structure of human 11beta-HSD1 with compound 6d (Ki=28 nM) revealed a large lipophilic pocket accessible by substitution off the 2-position of the thiazolone. To increase potency, analogues were prepared with larger lipophilic groups at this position. One of these compounds, the 3-noradamantyl analogue 8b, was a potent inhibitor of human 11beta-HSD1 (Ki=3 nM) and also inhibited 11beta-HSD1 activity in lean C57Bl/6 mice when evaluated in an ex vivo adipose and liver cortisone to cortisol conversion assay.     

2-(S)-phenethylaminothiazolones as potent, orally efficacious inhibitors of 11beta-hydroxysteriod dehydrogenase type 1

11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1) is the enzyme that converts cortisone to cortisol. A growing body of evidence suggests that selective inhibition of 11beta-HSD1 could potentially treat metabolic syndrome as well as type 2 diabetes. Through modification of our initial lead 1, we have discovered trifluoromethyl thiazolone 17. This compound had a Ki of 22 nM, possessed low in vivo clearance, and showed a 91% inhibition of adipose 11beta-HSD1 enzymatic activity in a mouse ex vivo pharmacodynamic model.     

11beta-hydroxysteroid dehydrogenase type 1 inhibitors for metabolic syndrome

The metabolic syndrome is a constellation of interrelated metabolic risk factors that appear to promote the development of diabetes and cardiovascular disease. These risk factors include abdominal obesity, insulin resistance, hypertension and dyslipidemia. 11beta-Hydroxysteroid dehydrogenase (11beta-HSD) catalyzes the interconversion of glucocorticoids through the activity of two isozymes: type 1 (11beta-HSD1) and type 2 (11beta-HSD2). 11beta-HSD1 converts inactive glucocorticoid to the active form, whereas 11beta-HSD2 converts active glucocorticoid to the inactive form. It is well established that reduced 11beta-HSD2 activity causes hypertension and electrolyte abnormalities. More recently, the pathophysiological role of 11beta-HSD1 has been explored and studies suggest that increased 11beta-HSD1 activity within target tissues may promote insulin resistance, obesity, hypertension and dyslipidemia. This review will discuss the evidence that inhibition of 11beta-HSD1 may be therapeutic in the treatment of the metabolic syndrome.     

Tissue-specific glucocorticoid reactivating enzyme, 11 beta-hydroxysteroid dehydrogenase type 1 (11 beta-HSD1)--a promising drug target for the treatment of metabolic syndrome

Obesity is closely associated with the Metabolic Syndrome, which includes insulin resistance, glucose intolerance, dyslipidemia and hypertension. The best predictor of these morbidities is not the total body fat mass but the quantity of visceral (e.g. omental, mesenteric) fat. Glucocorticoids play a pivotal role in regulating fat metabolism, function and distribution. Indeed, patients with Cushing-s syndrome (a rare disease characterized by systemic glucocorticoid excess originating from the adrenal or pituitary tumors) or receiving glucocorticoid therapy develop reversible visceral fat obesity. The role of glucocorticoids in prevalent forms of human obesity, however, has remained obscure, because circulating glucocorticoid concentrations are not elevated in the majority of obese subjects. Glucocorticoid action on target tissue depends not only on circulating levels but also on intracellular concentration. Locally enhanced action of gluccorticoids in adipose tissue and skeletal muscle has been demonstrated in the Metabolic Syndrome. Evidence has accumulated that enzyme activity of 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1), which regenerates active glucocorticoids from inactive forms and plays a central role in regulating intracellular glucocorticoid concentration, is commonly elevated in fat depots from obese individuals. This suggests a role for local glucocorticoid reactivation in obesity and the Metabolic Syndrome. 11beta-HSD1 knockout mice resist visceral fat accumulation and insulin resistance even on a high-fat diet. Furthermore, fat-specific 11beta-HSD1 transgenic mice, those have increased enzyme activity to a similar extent seen in obese humans, develop visceral obesity with insulin and leptin resistance, dyslipidemia and hypertension. In adipocytes, both antidiabetic PPARgamma agonists and LXRalpha agonists significantly reduce 11beta-HSD1 mRNA and enzyme activity, suggesting that suppression of 11beta-HSD1 in adipose tissue may be one of the mechanisms by which these drugs exert beneficial metabolic effects. Recently reported selective inhibitors of 11beta-HSD1 can ameliorate severe hyperglycemia in the genetically diabetic obese mice. In summary, 11beta-HSD1 is a promising pharmaceutical target for the treatment of the Metabolic Syndrome.     

Improved homogeneous proximity-based screening assay of potential inhibitors of 17beta-hydroxysteroid dehydrogenases

17beta-Hydroxysteroid dehydrogenases (17beta-HSDs) are substrate- and tissue-specific isoenzymes that regulate activation and inactivation of steroid hormones. Up-regulation and downregulation in expression of 17beta-HSDs are linked to onset of many steroid-dependent diseases, such as colon, prostate, and breast cancer; thus 17beta-HSDs are potential drug screening targets. Currently their enzymatic activities are usually measured using laborious chromatographic separations followed by radioactive detection of substrate and product. We have previously reported the use of a homogeneous luminescence resonance energy transfer-based immunoassay for 17beta-estradiol in screening of potential inhibitors of 17beta-HSD type 1 (17beta-HSD-1). By replacing the previously used cell-based enzyme reactions with recombinant enzyme reactions the sensitivity of the screening assay improved considerably. In addition, the single assay was able to detect the influence of a tested compound not only on 17beta-HSD-1 but also on 17beta-HSD type 2 (17beta-HSD-2), catalyzing the opposite reaction. The screening results of the tested molecules obtained from the optimized immunoassay were very similar when compared with the results of high performance liquid chromatography separation analysis. The Z factors were 0.79 and 0.83 for 17beta-HSD-1 and 17beta-HSD-2 assays, respectively. Thus the immunoassay measuring samples converted with the recombinant enzymes was a very suitable method for primary high throughput screening, and it could be used also in further characterization of potential drugs.     

Piperazine sulfonamides as potent, selective, and orally available 11beta-hydroxysteroid dehydrogenase type 1 inhibitors with efficacy in the rat cortisone-induced hyperinsulinemia model

11beta-Hydroxysteroid dehydrogenase type 1 (11beta-HSD1) is the enzyme that converts cortisone to cortisol. Evidence suggests that selective inhibition of 11beta-HSD1 could treat diabetes and metabolic syndrome. Presented herein are the synthesis, structure-activity relationship, and in vivo evaluation of piperazine sulfonamides as 11beta-HSD1 inhibitors. Through modification of our initial lead 5a, we have identified potent and selective 11beta-HSD1 inhibitors such as 13q and 13u with good pharmacokinetic properties.     

11beta-hydroxysteroid dehydrogenases: changing glucocorticoid action

11beta-hydroxysteroid dehydrogenases (11beta-HSDs) catalyse the interconversion of active cortisol and inert cortisone. Two isozymes have been discovered, each with unique properties and powerful biological roles. 11beta-HSD2 potently inactivates cortisol, protecting key tissues. By contrast, 11beta-HSD1 regenerates cortisol, amplifying its actions in liver, fat and brain. Overexpression of this isozyme may contribute to the pathogenesis of the metabolic syndrome. Its inhibition is a potential therapeutic target for both metabolic and glucocorticoid-associated CNS disorders.     

Development of 11beta-HSD1 inhibitors for the treatment of type 2 diabetes

Glucocorticoid action is linked to the development of obesity and insulin resistance. Inhibition of 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1) has been proposed as a strategy to suppress glucocorticoid action in a tissue-specific manner. A large variety of 11beta-HSD1 inhibitor classes are under investigation by the pharmaceutical industry to treat type 2 diabetes and obesity.     

Recommendations for the reduction of compound artifacts in time-resolved fluorescence resonance energy transfer assays

Time-resolved (TR) fluorescence resonance energy transfer (FRET) is a widely accepted technology for high throughput screening (HTS), being able to detect and quantify the interactions of specific biomolecules in a homogeneous format. TR-FRET has several advantages for HTS applications that reduce assay artifacts such as compound interference. However, in some cases artifacts due to compound autofluorescence, color quenching, or signal stability are still observed. This report presents strategies addressing these issues by several means. One recommendation is the recording and visualization of differences in the donor/acceptor fluorescence, which allows the identification of compound artifacts. Another suggestion is to adjust the time delay, between excitation and recording of the fluorescence, in order to reduce compound interference. Furthermore, configuring the assay to allow the TR-FRET measurement to be taken at different time points, creating a reaction time course, allows background correction for each sample. Finally, the optimization of the FRET pair, to ensure assay signal stability under screening conditions, can improve the assay quality. This report presents examples of how these simple steps can be applied to enhance the quality of TR-FRET screening campaigns.     

Sterenin A, B, C and D, novel 11beta-hydroxysteroid dehydrogenase type 1 inhibitors from Stereum sp. SANK 21205

The novel 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1) inhibitors known as sterenin A, B, C and D were found in a solid-state culture of the producing basidiomycetes identified as Stereum sp. SANK 21205. Purification of the 50% aq Me(2)CO extract of the culture was performed by EtOAc extraction, reversed phase open-column chromatography and successive ODS HPLC preparation. These compounds, whose structures were determined by several spectroscopic methods, were found to be novel isoindolinone alkaloids which exhibited potent selective inhibitory activities against 11beta-HSD1.     

Role of 11-beta-hydroxysteroid dehydrogenase type 1 in differentiation of 3T3-L1 cells and in rats with diet-induced obesity

AIM: To observe the roles of 11-beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1) in in vitro preadipocyte differentiation and in rats with diet-induced obesity (DIO). METHODS: Protein expression of 11beta-HSD1 in the process of 3T3-L1 cell differentiation and in various tissues of the rats were detected by Western blot analysis; expression of 11beta-HSD1 mRNA and glucocorticoid receptor (GR) and other marker genes of preadipocyte differentiation were detected by using real-time PCR. RESULTS: Lipid droplets in 3T3-L1 cells accumulated and increased after stimulation. A dramatically elevated protein level of 11beta-HSD1, especially in the late stages of 3T3-L1 cell differentiation, was detected. The relative mRNA levels of 11beta-HSD1, GR and cell differentiation markers LPL, aP2, and FAS were upregulated, and Pref-1 was downregulated during the differentiation. In DIO rats, bodyweight, visceral adipose mass index and the protein expression of 11beta-HSD1 increased, especially in adipose tissue, brain and muscles. Serum insulin, triglyceride, total cholesterol and low-density lipoprotein cholesterol were found to be increased in DIO rats, but without any obvious changes in blood glucose or tumor necrosis factor-alpha levels. CONCLUSION: 11beta-HSD1 may promote preadipocyte differentiation, and may be involved in the development of obesity.